We watched ____ television all through the night.

Certain nouns that name institutions, activities, or broadcast media — school, bed, prison, radio, television — take the zero article (no “a”, “an”, or “the”) when they refer to the general institution or medium itself rather than one specific physical object. This zero-article pattern marks the noun as being used in its abstract, functional sense, not as a countable, particular item that has been introduced or identified.

In “We watched ____ television all through the night,” “television” names the broadcast medium — the activity of watching TV programmes in general — not one particular television set. The standard idiom for this generic sense is “watch television” with no article at all, so the blank is correctly left empty.

• “the” would need a definite, already-identified set to point to (e.g. “switch off the television”); nothing earlier in the sentence identifies any particular set.

• “a” would introduce “television” as one, previously-unmentioned countable appliance, but the noun is not naming a single physical set in this sentence.

• “an” fails on its own terms too: “an” precedes a vowel SOUND, and “television” opens with the consonant sound /t/, so “an television” is never grammatical.

Since the sentence uses “television” in its generic, broadcast-medium sense rather than as a specific countable object, the correct completion leaves the blank without any article.